Foot - Lecture Notes

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Lecture 1
Lecture 2

Foot

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1. Demonstrate the continued course of leg muscles, nerves, and vessels into the foot.
Anterior: The anterior tibial a. continues through the anterior of the ankle becoming the dorsal pedal a. following the path of the deep fibular n. Extensor digitorum longus, extensor hallucis and tibialis anterior also cross at the anterior side of the ankle.
Lateral: Fubularus longus, and brevis pass inferior to the lateral malleous to enter the foot.
Medial: tibialus anterior, flexordigitorus longus, and flexor hallucis longus pass inferior to the medial malleous to enter the foot. Posterior tibial a. enters the foot medially as well to become the medial and lateral plantar a. The posterial tibial nerve also follows this path.
Posterior: The calcaneal tendon crosses porteriorly to attach to the calcaneus.

2. Understand the function of intrinsic foot muscles.
The Intrinsic foot muscles lie within the foot and act primarily in stabilizing the foot in locomotion. They exist on the dorsum of the foot and in four layers on the plantar foot.
Dorsum:

Muscle	Innervation	Origin	Insertion	Action
Extensor Digitorum Brevis	Deep Fibular n.	Calcalneus	Extensor expansion of toes 2-4	Extends toes 2-4
Extensor Hallucis Brevis	Deep Fibular n.	Calcalneus	Prox. phalanx of great toe	Extends great toe

Plantar layer 1 (suprificial):

Muscle	Innervation	Origin	Insertion	Action
Flexor Digitorum Brevis	Medial plantar n.	Calcaneus	Lateral 4 toes	Flex toes 2-5
Abductor Hallucis	Medial plantar n.	Calcaneus	Great toe	Abduct great toe (Important to weight-bearing)
Abductor Digiti Minimi	Lateral plantar n.	Calcaneus	Little toe	Abduct little toe (Important to weight-bearing)

Plantar layer 2:

Muscle	Innervation	Origin	Insertion	Action
Quadratus Plantae	Lateral plantar n.	Calcaneus	Tendon of Flexor Digitorum Longus	Flex toes 2-5
Lumbricals (4)	Medial (1st) and Lateral plantar n (2nd-4th)	Tendon of Flexor Digitorum Longus	Dorsum surface of extensor expansion 2-5	Flex metatarsophalangeal joint Extend PIP and DIP of digits 2-5

Plantar layer 3:

Muscle	Innervation	Origin	Insertion	Action
Flexor Hallucis Brevis (2 heads)	Medial plantar n.	(cuboid, lateral cuneiform, medial side of the first metatarsal)	(medial belly: medial side of proximal phalanx of the great toe) lateral belly: lateral side of the proximal phalanx of the great toe)	Flex metatarsophalangeal joint of great toe
Flexor Digiti Mini Brevis	Lateral plantar n.	(base of 5th metatarsal bone)	(proximal phalanx of 5th digit)	Flex metatarsophalangeal joint of little toe
Adductor Hallucis (2 heads)	Lateral plantar n.(deep branch)	(oblique head: bases of metatarsals 2-4 transverse head: heads of metatarsals 3-5)	1st Metatarsal (lateral aspect)	Adduct great toe

Plantar layer 4 (deep):

Muscle	Innervation	Origin	Insertion	Action
Plantar Interossei (3) PAD	Lateral plantar n. (deep branch)	Medial side metatarsal 3-5	Prox. phalange 3-5	Adduction
Dorsal Interossei (4) DAB	Lateral plantar n. (deep branch)	Shafts of adjacent metatarsal bones	Bases of the proximal phalanges for digit 2 (both sides) & digits 3,4 (lateral side)	Abduction

3. Define the arches of the foot and understand how each is maintained.
Medial longitudinal arch: Formed by interlocking of the talus, calcaneus, navicular, cuneiform bones, and three medial metatarsal bones. Head of Talus acts as keystone and is supported by spring ligament and tendon of flexor hallucis longus.

Lateral longitudinal arch: Formed by calcaneus, cupoid bone, and lateral two metatarsal bones. The keystone is the cuboid bone and it is supported by the Fibularis longus tendon and the long+short plantar ligaments. (spring ligament)

Transverse arch(proximal): Formed by navicular bone,the three cuniform bones, cuboid bone, and the base of the five metatarsal bones. Supported by tendon on fibularis longus.

Transverse arch(distal): Formed by the heads of the five metatarsal bones and supported by the transverse head of the adductor hallucis.

4. Define the role of the plantar aponeurosis.

The plantar aponeurosis are longitudinally arranged bands of dense fibrous connective tissue that supports the longtitudinal arches of the foot, holds the parts of the foot together, and helps protect the plantar surface from injury. The plantar aponerosis arises posteriorly from the calcaneus and divides into five bands that split and enclose the digital tendons that attach to the margins of the fibrous digital sheaths and the sesamoid bones of the big toe.